Conventionally, for example, in etching devices, a magnetron type plasma generation device using a magnet, an ECR discharge type plasma generation device using electron cyclotron resonance and a helicon type plasma generation device using a helicon wave have been mainly used.
As a plasma generation device, patent document 1 discloses a device in which a plurality of permanent magnets magnetized along a ring-shaped center axis is concentrically arranged on the upper wall of a plasma generation chamber so as to have alternate polarities, and in which a magnetic coil is further arranged outside the side wall of the plasma generation chamber. In the device, a coil magnetic field is generated such that magnetic field lines are pointed to the side of a substrate by the magnetic coil arranged on the side wall, and thus a plasma generated in the vicinity of the upper wall of the plasma generation chamber is widely diffused by the coil magnetic field.
Moreover, patent document 2 discloses a device in which a substrate holder connected to a self-bias generation high frequency power supply is arranged sufficiently away from a plasma generation high frequency electrode, and in which magnetic coils are arranged both outside a vacuum vessel between the high frequency electrode and the substrate holder and on the back surface of the high frequency electrode, respectively. The device freely controls the self bias and performs stable plasma processing without damaging an item to be processed.
Another method of realizing the uniformity of plasma is to concentrically and triply arrange cylindrical permanent magnets that are magnetized in the direction of the center axis of the cylinder (in the longitudinal direction of the cylinder) so as to have alternate polarities. In this case, a boundary surface (separatrix) formed between magnetic field lines formed by two cylindrical permanent magnets (permanent magnets in the center and the outermost side) arranged outside and magnetic field lines formed by two cylindrical permanent magnets (permanent magnets in the center and the innermost side) arranged inside is produced within a vacuum vessel. Since the plasma expands in the inside surrounded by the separatrix, strength of the permanent magnet is optimized and thus it is possible to control the diffusion region of the plasma and adjust the uniformity. This type of magnetic field generation device is proposed, and is applied to a planar type ECR device and the like (see patent document 3).